Effects of Elevated Temperature on Splitting Tensile Strength of OPC and BLA Pozzolanic Concrete and Mortar (original) (raw)
Related papers
Effect of elevated temperature on physico-mechanical properties of blended cement concrete
Construction and Building Materials, 2011
This study aims to investigate the effect of thermally treated temperatures up to 800 °C on the physical properties, microstructure and phase composition of pozzoloanic cement pastes. Pozzolanic cement was prepared from three different pozzolans, namely silica fume (SF), ground granulated blast-furnace slag (WCS) and ground clay bricks (GCB). The samples were subjected to heat treatment at the rate of 10 o C/min, and then kept for 3 hours from 200 up to 800 o C, then cooled to the room temperature in the furnace switched off. It was concluded that the cement paste M.10 (70 % OPC + 10 % WCS + 10 % GCB + 10 % SF) is the optimum mix which gives a higher compressive strength up to 600 °C. It was also found that M.10 has more hydration products than other mixes. The microstructure shows a massive dense closed texture, with the lower number of voids and pore size, with the formation of inner fibers and crystalline needle like CSH hydrated which is responsible for the increase in compressive strength up to 500 °C. 158 thereby causing progressive breakdown of cement gel structure, reduced durability, increased tendency of drying shrinkage, structural cracking and associated aggregate colour changes [1].
2021
Concrete is a construction material composed of cement, fine aggregates (sand) and coarse aggregates mixed with water which hardens with time. Cement is an important constituent in the concrete composite; however, its cost is relatively very high, this has impacted in the cost of concrete production and by extension on the cost of housing delivery in Nigeria. Rice husk ash is one of the promising pozzolanic materials that can be blended with Portland cement for the production of durable concrete and at the same time a value-added product. the use of the rice husk ash as partial replacement to cement in concrete not only improve the strength of concrete, protection against cracking, spalling, reduce density and porosity of the concrete. It also reduce the emission of carbon monoxide to the environment which is very dangerous to the atmosphere. The elevated temperature is one of the most harmful effects that cause durability problems in construction; this effect can cause permanent damage in construction and reduce the service life. This paper reviews the work presented by various researchers on effect of elevated temperature on the durability and strength properties of concrete using rice husk ash as partial replacement. From the available literature reviewed, there is a possible research gab in investigating the effect of elevated temperature on concrete with rice husk ash as partial replacement to cement, because most of the researchers have focused on conventional concrete, whereas concrete with rice husk ash as replacement to cement have been recommended for use with a replacement value of 10-20%. The degree of its performance of these recommended replacement needs to be investigated.
Effect of elevated temperature on compressive strength of blended cement mortar
High temperature rise mostly caused by a fire outbreak is currently becoming a threat that endangers concrete's structural performance for buildings and the safety of occupants. The behavior of concrete after fire subjection has been of much interest for the structural materials design purposes. This study investigated the physical properties and the compressive strength of M25 concrete incorporating Neem Seed Husk Ash (NSHA), exposed to and through targeted different levels of temperature (200 • C to 800 • C) for a period of three hours in an electric furnace. The NSHA was produced by calcining neem seed husks at 800 • C for six hours and then sieved through the 125 µm sieve. Different amounts of NSHA were investigated while considering the plain concrete as the control sample. 150 concrete cubes of 150 mm sizes were cast and properly cured for 7 and 28 days. The experimental results show that the compressive strength of the 5% NSHA concrete exposed to temperatures up to 400 • C is 21.3% and 23.8% better than the normal concrete at 7 and 28 curing days, respectively. Surface cracks and spalling are noticeable at 600 • C and 800 • C for all samples considered in this study.
Split Tensile Strengths of Concrete Incorporating Rice Husk Ash and SawDust Ash
Journal of Multidisciplinary Engineering Science and Technology (JMEST) ISSN: 2458-9403 Vol. 3 Issue 7, 2016
This work investigated the split tensile strengths of concrete containing rice husk ash (RHA) and saw dust ash (SDA). RHA and SDA were obtained from open air calcination. Ordinary Portland cement (OPC) was partially replaced with each of RHA, SDA, and RHA-SDA at 5%, 10%, and 15%. Nine concrete cylinders of dimensions 150×300mm were produced using 100% OPC. Eighty one concrete cylinders also of dimensions 150×300mm were similarly produced for each of the percentage replacement of OPC with RHA, SDA, and RHA-SDA, making a total of 252 concrete cylinders. The concrete cylinders were cured by immersion and tested for split tensile strength at 28, 90, and 150 days. Models were developed to predict the tensile strengths of concrete containing RHA and SDA as binary and ternary blends with OPC at varying percentage replacements and curing ages. The split tensile strength decreased with increasing percentage replacements of OPC with RHA, SDA, and RHA-SDA. At 28 days of curing, values of 0.86N/mm 2 , 0.78N/mm 2 , and 0.70N/mm 2 were obtained at 5%, 10%, and 15% replacements of OPC with RHA respectively. Values of 0.77N/mm 2 and 0.58N/mm 2 were obtained at 5% and 10% replacements of OPC with SDA respectively. Values of 0.82N/mm 2 and 0.64N/mm 2 were obtained at 5% and 10% replacements of OPC with RHA-SDA respectively. Split tensile strengths of concrete with RHA, SDA, and RHA-SDA were lower at early age of curing but improved at later ages. For 5% replacement of OPC with RHA values of 1.42N/mm 2 and 1.85N/mm 2 were obtained at 90 and 150 days of curing respectively. For 5% replacement of OPC with SDA values of 1.28N/mm 2 and 1.65N/mm 2 were obtained at 90 and 150 days of curing respectively. For 5% replacement of OPC with RHA-SDA values of 1.35N/mm 2 and 1.66N/mm 2 were obtained at 90 and 150 days of curing respectively. Values for the control were 1.34N/mm 2 and 1.61N/mm 2 at 90 and 150 days of curing respectively. Thus, based on split tensile strength values, concrete produced with 5% to 15% replacement of OPC with RHA and 5% to 10% replacement of OPC with RHA-SDA could be used in reinforced and unreinforced concrete works where time of loading is not critical. The models developed were tested and found to be adequate for predicting split tensile strengths of binary and ternary blended OPC-RHA-SDA cement concretes.
Effect of Elevated Temperature on Mechanical Properties of Limestone, Quartzite and Granite Concrete
International Journal of Concrete Structures and Materials, 2016
Although concrete is a noncombustible material, high temperatures such as those experienced during a fire have a negative effect on the mechanical properties. This paper studies the effect of elevated temperatures on the mechanical properties of limestone, quartzite and granite concrete. Samples from three different concrete mixes with limestone, quartzite and granite coarse aggregates were prepared. The test samples were subjected to temperatures ranging from 25 to 650°C for a duration of 2 h. Mechanical properties of concrete including the compressive and tensile strength, modulus of elasticity, and ultimate strain in compression were obtained. Effects of temperature on resistance to degradation, thermal expansion and phase compositions of the aggregates were investigated. The results indicated that the mechanical properties of concrete are largely affected from elevated temperatures and the type of coarse aggregate used. The compressive and split tensile strength, and modulus of elasticity decreased with increasing temperature, while the ultimate strain in compression increased. Concrete made of granite coarse aggregate showed higher mechanical properties at all temperatures, followed by quartzite and limestone concretes. In addition to decomposition of cement paste, the imparity in thermal expansion behavior between cement paste and aggregates, and degradation and phase decomposition (and/or transition) of aggregates under high temperature were considered as main factors impacting the mechanical properties of concrete. The novelty of this research stems from the fact that three different aggregate types are comparatively evaluated, mechanisms are systemically analyzed, and empirical relationships are established to predict the residual compressive and tensile strength, elastic modulus, and ultimate compressive strain for concretes subjected to high temperatures.
Effect of rice straw ash and palm leaf ash on the properties of ultrahigh-performance concrete
Case Studies in Construction Materials,, 2022
The global expansion of agricultural production has increased the amount of agricultural waste (AW). Accordingly, AW should be disposed of properly to preserve the environment. This study focuses on using rice straw ash (RSA) and palm leaf ash (PLA) as partial replacement for cement in the production of ultrahigh-performance concrete (UHPC). In particular, this research investigates the effect of using RSA and PLA as pozzolanic materials on the microstructure and the fresh, mechanical and physical properties of UHPC. Eleven UHPC mixtures are prepared as control mixtures without RSA and PLA. Five mixtures are used with 10%, 20%, 30%, 40% and 50% RSA, whilst five residual mixtures contain 10%, 20%, 30%, 40% and 50% PLA. Results indicate the efficiency of RSA or PLA as a partial substitute (i.e. 20% of cement weight), with mechanical properties and durability better than those of the reference mixture. The microstructure analysis shows that 20% RSA or PLA yields denser concrete than the control mixture. The UHPC samples with 20% RSA and 20% PLA achieve the best results of 188.5 MPa and 185 MPa by increasing compressive strength by about 13.2% and 11.1%, respectively, compared with the control mixture at a test age of 28 days. Important mechanical properties, such as splitting tensile strength, flexural strength and modulus of elasticity, exhibit a trend similar to that of the compressive strength results for all the UHPC mixtures. The average values of splitting tensile strength and flexural strength at 28 days are about 11% and 14% of the compressive strength of the same UHPC mixtures, respectively. The significance of the current study is the relatively high cement replacement percentages of up to 50% by weight and the use of AW as replacement materials.
2021
This paper presents the effects of variability in the chemical and elemental composition of Rice Husk Ash (RHA) sourced from four (4) different locations on Tensile Properties of Concrete. RHA is an agricultural waste gotten from rice mills after removal of rice paddy for food and burnt in open air or under controlled processes. RHA is found to be pozzolanic and can be used to partially replace cement to enhance the strength and quality of concrete. The different sources where RHA was gotten are; Ogoja, Abakaliki, Adani and Adikpo in Nigeria. It is discovered that the pozolanic properties of RHA varies based on their source location. Samples from Ogoja where found to have the highest pozzolanic properties followed by Abakaliki, Adani, and Adikpo, their silica content was found to be 84.55, 76.3, 70.12, 70.11, respectively. RHA was used to replace cement in concrete at 5, 10,15,20,25 and 30%. The compressive strength was determined and the values are as follows; And the compressive strength values at 28 days was found to be in the range of 37-42N/mm2 at 5%RHA, 35-39.5N/mm2 at 10%RHA, 30-34.5N/mm2 at 15%RHA, 27-29N/mm2 at 20%RHA, 22-25.6N/mm2 at 25% RHA and 21-24N/mm2 at 30% RHA compared to the controlled sample with a strength value of 42.64N/mm2. Cylindrical columns concrete of size 100mm diameter by 200mm long were moulded and stored in water for 28 days before testing for tensile splitting strength. The values determined from the split tensile test are as follows; 2.1-3.1N/mm2 at 5%RHA, 2.1-2.5N/mm2 at 10% RHA, 1.8-2.10 N/mm2 at 15% RHA, 1.2-1.7 N/mm2 at 20%RHA, 1.1-1.3 N/mm2 at 25% RHA and 0.62-0.9 N/mm2 at 30% RHA while the results of the controlled sample is 3.1 N/mm2.From the results above it can be deduced that source location influences the chemical properties of RHA strength characteristics of the Concrete with RHA as partial replacement.
Rice husk ash (RHA) is an agro waste and a natural pozzolana which is rich in silica and found in abundance globally. This research considered the pozzolanic properties of RHA from Seven different sources in Nigeria (Ogoja, Abakaliki, Adani, Adikpo, Obubra, Makurdi and Vandikya). It is discovered that the elemental chemical composition of this natural pozzolan varies based on their location. Samples from Ogoja were found to have the highest pozzolanic properties followed by Abakaliki, Adani, Adikpo, Obubra, Makurdi and Vandikya. Their silica content was found to be84.55%, 76.3%, 70.12%, 70.11%, 64.67%, 55.55%, and 48.4% respectively. Four out of the seven samples with the highest pozzolanic values were used as partial replacements for ordinary Portland cement at 5, 10, 15, 20, 25, and 30% replacement levels. Concrete mix ratio of 1:1.5:3 was adopted and the compressive strength values at 28 days were found to be in the range of 37-42N/mm 2 at 5%RHA, 35-39.5N/mm 2 at 10%RHA, 30-34.5N/mm 2 at 15%RHA, 27-29N/mm 2 at 20%RHA, 22-25.6N/mm 2 at 25% RHA and 21-24N/mm 2 at 30% RHA compared to the controlled sample with a strength value of 42.64N/mm 2 .
2008
This study aims to investigate the effect of thermally treated temperatures up to 800 °C on the physical properties, microstructure and phase composition of pozzoloanic cement pastes. Pozzolanic cement was prepared from three different pozzolans, namely silica fume (SF), ground granulated blast-furnace slag (WCS) and ground clay bricks (GCB). The samples were subjected to heat treatment at the rate of 10 o C/min, and then kept for 3 hours from 200 up to 800 o C, then cooled to the room temperature in the furnace switched off. It was concluded that the cement paste M.10 (70 % OPC + 10 % WCS + 10 % GCB + 10 % SF) is the optimum mix which gives a higher compressive strength up to 600 °C. It was also found that M.10 has more hydration products than other mixes. The microstructure shows a massive dense closed texture, with the lower number of voids and pore size, with the formation of inner fibers and crystalline needle like CSH hydrated which is responsible for the increase in compressive strength up to 500 °C. 158 thereby causing progressive breakdown of cement gel structure, reduced durability, increased tendency of drying shrinkage, structural cracking and associated aggregate colour changes [1].